The first thing to look for when doing legislative history research is a compiled legislative history. A compiled legislative history brings together all the various legislative documents related to a Public Law in one place, making your job a lot easier. The first thing you'll want to have is the Public Law # of the law you're interested in. This can be found in an Annotated Code or sometimes on the web. Once you have the Public Law #, you can search the resources below for compiled legislative histories.
If you do not find a compiled legislative history, you can create your own by gathering the documents discussed in the tabs above.